1. Field of the Invention
The present invention relates to radio-frequency (RF) controlled devices, and more specifically, to RF load control devices for motorized roller shades.
2. Description of the Related Art
Control systems for controlling electrical loads, such as lights, motorized window treatments, and fans, are known. Such control systems often use radio-frequency (RF) transmission to provide wireless communication between the control devices of the system. One example of an RF lighting control system is disclosed in commonly-assigned U.S. Pat. No. 5,905,442, issued on May 18, 1999, entitled METHOD AND APPARATUS FOR CONTROLLING AND DETERMINING THE STATUS OF ELECTRICAL DEVICES FROM REMOTE LOCATIONS, the entire disclosure of which is incorporated herein by reference.
The RF lighting control system of the '442 patent includes wall-mounted load control devices, table-top and wall-mounted master controls, and signal repeaters. Each of the load control devices includes a user interface and an integral dimmer circuit for controlling the intensity of an attached lighting load. The user interface has a pushbutton actuator for providing on/off control of the attached lighting load and a raise/lower actuator for adjusting the intensity of the attached lighting load. The table-top and wall-mounted master controls have a plurality of buttons and are operable to transmit RF signals to the load control devices to control the intensities of the lighting loads. The signal repeaters help to ensure error-free communication such that every component of the system will receive the RF communication signals intended for that component.
The control devices of the RF lighting control system include RF antennas adapted to transmit and receive the RF signals that provide for communication between the control devices of the lighting control system.
It is desirable to control the position of motorized window treatments, such as roller shades, as part of the RF lighting control system. Standard motorized roller shades comprise a flexible shade fabric wound around a roller tube. The roller tube is rotated by a motor, which is controlled by a controller. Preferably, the controller and the motor are located in an enclosure that is mounted inside of the roller tube. The controller must include an antenna and an RF transceiver in order to communicate with the components of the RF lighting control system. An example of a motorized roller shade for a wired control system is disclosed in commonly-assigned U.S. Pat. No. 6,983,783, issued Jan. 10, 2006, entitled MOTORIZED SHADE CONTROL SYSTEM, the entire disclosure of which is hereby incorporated by reference.
However, a typical roller tube is made of metal that acts as a shield which interferes with the RF communications. The roller tube attenuates the external RF signals that the antenna and the RF transceiver should receive. Also, since the enclosure is located inside the roller tube, noise from internal sources, such as motor brushes and switching circuits (such as, for example, switching power supplies) is directed towards the RF transceiver and increases detection errors at the RF transceiver. Accordingly, reliable RF communications are typically difficult to establish between the RF controller of the motorized roller shade and the other control devices of the RF lighting control system.
Therefore, there is a need for a motorized roller shade that is operable to reliably communicate in an RF control system. Specifically, there is a need for a motorized roller shade that has a controller and an RF transceiver mounted inside the roller tube and an antenna that allows for reliable communications with the RF transceiver.